The present invention relates to a headlamp for a vehicle having a discharge bulb.
Headlamps for vehicles have recently begun to use a discharge bulb capable of high-luminance illumination as a light source bulb. A headlamp for a vehicle equipped with such a discharge bulb requires a lighting circuit unit for lighting the discharge bulb and, as shown in FIG. 4, this lighting circuit 2 is often attached to an outer surface of a lower wall 4a of a lamp body 4. When the lighting circuit 2 is attached to the outer surface of the lower wall 4a of the lamp body 4, it is necessary to ensure that the lighting circuit is waterproofed so that water does not enter the interior of the lighting circuit unit 2. Water may attempt to enter during high-pressure car washing or traveling in rainy weather, and if successful, would cause a failure of the lighting circuit. Thus, conventional lamp designs using lighting circuit units become complex and expensive to manufacture.
In addition, the lighting circuit unit 2 is relatively heavy, and if a completely waterproof design is adopted for this unit, its weight becomes very large. When the lighting circuit is heavy, the lower wall 4a of the lamp body 4 is liable to undergo flexing and deform due to the weight of the lighting circuit unit 2, with the result that a lens seal groove 4b of the lamp body 4 is also liable to become deformed. If deformation occurs in the lens seal groove 4b, there is a possibility that faulty sealing occurs between the lamp body 4 and a front lens 6.
The present invention has been devised to address the above-described circumstances, and provides a headlamp for a vehicle in which a lighting circuit unit is attached to an outer surface of a lower wall of a lamp body in a waterproof manner.
The structure ensures that water will not affect the lighting circuit unit which enables the lighting circuit unit to be made with light weight and at low cost. The light weight makes it possible to effectively prevent the occurrence of faulty sealing between the lamp body and the front lens.
The invention includes attaching a predetermined unit cover on the outer surface of the lower wall of the lamp body, and forming a predetermined upright wall at a position located forwardly of the unit cover. In accordance with a first aspect of the invention, a headlamp for a vehicle having a reflector for supporting a discharge bulb in a lamp chamber formed by a lamp body and a front lens includes a lighting circuit unit for lighting the discharge bulb attached to an outer surface of a lower wall of the lamp body. A unit cover attached to the outer surface of the lower wall covers the lighting circuit unit, and an upright wall formed on the lamp body in front of the unit cover projects downward to a position lower than that surface of a front end portion of the unit cover.
In accordance with a second aspect of the invention, in the headlamp for a vehicle according to the first aspect of the invention, the upright wall is formed on an outer wall portion of a lens seal groove where the front lens is attached in the lamp body.
The lighting circuit unit and the unit cover may be respectively arranged to be attached to the lamp unit independently, or the unit cover and lighting circuit may be a unit that together are attached to the lamp unit.
As long as the upright wall is formed over a range at least wider than the horizontal width of the unit cover, the width of the upright wall is not particularly limited.
As shown in the above-described arrangement, the headlamp for a vehicle in accordance with the invention is structured such that although a lighting circuit unit is attached to an outer surface of a lower wall of the lamp body, a unit cover covering the lighting cirucit unit is attached to the outer surface of the lower wall, and an upright wall is formed on the lamp body forwardly on the unit cover in such a manner as to project downward to a position lower than that surface of a front end portion of the unit cover. Therefore, it is possible to obtain the following advantages in operation.
Since the unit cover is attached to the outer surface of the lower wall of the lamp body, even if the lighting circuit unit is not provided with a completely waterproof structure, the sealing property for sealing between the lamp body and the unit cover can be secured, so that it is possible to prevent the entrance of water into the interior of the lighting circuit unit. Therefore, the structure of the lighting circuit unit can be simplified, thereby making it possible to lower the weight of the lighting circuit unit and attain a reduction in cost.
In addition, since an upright wall is formed on the lamp body in front of the unit cover in such a manner as to project downwardly to a position lower than that surface of a front end portion of the unit cover which opposes the lamp body unit, it is possible to prevent water from being splashed against the contact surfaces of the unit cover and the lamp body from the forward direction during high-pressure car washing or traveling in rainy weather. Accordingly, it is possible to prevent a situation where water enters the interior of the unit cover through the contact surfaces of the unit cover and the lamp body and wet the lighting circuit unit.
Furthermore, the upright wall reduces the possibility of the lens seal groove of the lamp body becoming deformed due to the weight of the lighting circuit unit (although its weight is alleviated to some extent, as mentioned above).
Accordingly, a headlamp in accordance with the invention where the lighting circuit unit is attached to the outer surface of the lower wall of the lamp body makes it possible to ensure waterproofness for the lighting circuit unit and structure the lighting circuit unit with light weight at low cost. At the same time, it is possible to effectively prevent the occurrence of faulty sealing between the lamp body and the front lens.
In the above-described arrangement, as stated in the second aspect of the invention, if the upright wall is formed on the outer wall portion of the lens seal groove, it is possible to enhance the rigidity of the portion surrounding the lens seal groove of the lamp body. Consequently, it is possible to prevent the deformation of the lens seal groove of the lamp body more effectively. In addition, since the outer wall portion of the lens seal groove is generally at a position lower than the lower wall of the lamp body, the vertical length of the upright wall can be set to be slightly shorter.
The above features and advantages of the present invention will become more apparent from the following detailed description of the invention when read in conjunction with the accompanying drawings.